Pulsed electromagnetic fields (PEMF) for treating therapeutically resistant problems of the musculoskeletal system are typically low-energy, time-varying magnetic fields. PEMF therapy has been used to treat non-union bone fractures and delayed union bone fractures. Non-union bone fractures are typically defined as injuries which have not satisfactorily healed within nine months or more after the trauma which caused the injury. Delayed union fractures are typically considered injuries which have not satisfactorily healed within nine months or less after the trauma which caused the associated injury. PEMF therapy has also been used for treatment of corresponding types of body soft tissue injuries.
PEMF therapy has been satisfactorily used in treating spinal fusion, failed arthrodeses, osteonecrosis, and chronic refractory tendinitis, decubitus ulcers and ligament, tendon injuries, osteoporosis, and Charcot foot. During PEMF therapy, an electromagnetic transducer coil is generally placed in the vicinity of the musculoskeletal injury (sometimes referred to as the "target area") such that pulsing the transducer coil will produce an applied or driving field that penetrates to the underlying damaged bone or other body tissue.
Present day PEMF transducers use a substantial amount of energy. In order to account for such energy use, present products may use a rechargeable battery pack, such as either a nickel cadmium or nickel metal hydride battery. Rechargeable battery packs are expensive, heavy, and must be carried by the patient. Many existing PEMF therapy systems must be recharged frequently, which increases the cost and inconvenience of operating such PEMF therapy systems.
The weight of many PEMF bone growth stimulators is generally proportional to the size of the batteries used to power the electrical circuitry as well as by the windings used to generate the output signal. Patient comfort while using such devices is often inversely proportional to the weight. Reducing the battery size and weight will help to reduce the weight and cost of such equipment and improve the patient's comfort.
Recently, ultrasound-based equipment has been used to accelerate healing of body tissue. Ultrasound therapy may also be used for treating non-union and delayed union fractures.